BBs can go down with surprisingly few torps, but I play GWX so perhaps the sinking mechanic helps quite a lot
. I once came across HMS Ramillies in a convoy and managed to get a hit on her bow, and another lucky hit right on her stern. She listed and after about half and hour went to the bottom.
A really important thing is to spread the torps along the length of the ship and not try to hit the same spot unless you know for sure it's a critical hit area (like under the turrets). I find fore and aft are good points to attack and can get you surprising tonnage even with one fish on big merchants after some time to allow for sinking
